sendmail Configuration problem

Hi,
I use hylafax-4.1beta1 on RedHat Linux 6.0
I have a bit of a problem when I try to configure my system to forward the
e-mail messages designated to user@phone_number.fax to faxmail utility. It
only works when I send the message from localhost. When I send an email
message from the host that runs sendmail and hylafax software everithing
works fine. The message is delivered through the faxmail program and goes
through without any problem. When I try to send the e-mail message from
another host in the local network it is accepted by sendmail but it is
making a DNS lookup on the hostname from the email adress and of course it
fails and I receive the "Host not found" error message from sendmail.
What should I do to make it work...
Any help will be greatly appreciated,
Thanks in advance,
Gabi Bota
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com